Women in Love by D. H. Lawrence

Ursula and Gudrun Brangwen are two sisters living in the Midlands of England. Ursula is a teacher, Gudrun an artist. They meet two men who live nearby, school inspector Rupert Birkin and coal-mine heir Gerald Crich. The four become friends. Ursula and Birkin become involved, and Gudrun eventually begins a love affair with Gerald.